Short Answer

Both the model and the market overwhelmingly agree that Democrats winning Illinois's 5th District by 31 or more points is most likely, with only minor residual uncertainty.

1. Market Behavior & Drivers

The price chart for this market shows a dramatic and rapid upward trend. Starting from a low of 1.0%, the market's probability surged in early May 2026. A minor 8.0 percentage point spike on May 05, 2026, was immediately followed by an extremely large 68.0 percentage point spike on May 06, 2026. This pushed the price from the low single digits to over 80.0% in a very short time frame. Since this major move, the price has stabilized and is currently holding steady at 91.0%.
According to the provided context, there was no specific news, social media narrative, or public announcement that directly corresponds to or explains the major price spikes on May 05 and May 06. The sample data indicates these movements occurred on zero trading volume, which suggests the price shift may not have been the result of broad market conviction at that precise moment. However, the price has since established a firm support level around 91.0%, indicating that the market has accepted this new valuation. The current high price reflects an overwhelming market consensus and strong sentiment that the "YES" outcome is highly probable.
  • D+19 Cook PVI and recent outcomes point to large Democratic victory.
  • IL-05 is rated "Solid Democratic" and consistently favors Democrats.
  • Upcoming filing deadline, primary, and general elections are key catalysts.
  • Rep. Quigley's potential retirement could significantly alter race dynamics.
  • President Biden's approval rating may present challenges for Democrats.

Who Wins and Why

Outcome Market Model Why
Democrats, 31+ pts 91.0% 91.7% The district's D+19 Cook Partisan Voting Index and recent +38 to +40 point margins indicate a large Democratic victory.
Democrats, 34+ pts 84.0% 85.2% The district's D+19 Cook Partisan Voting Index and recent +38 to +40 point margins indicate a large Democratic victory.
Democrats, 55+ pts 14.0% 5.0% The district's D+19 Cook Partisan Voting Index and recent +38 to +40 point margins indicate a large Democratic victory.
Democrats, 37+ pts 74.0% 75.9% The district's D+19 Cook Partisan Voting Index and recent +38 to +40 point margins indicate a large Democratic victory.
Democrats, 40+ pts 0.0% 17.6% The district's D+19 Cook Partisan Voting Index and recent +38 to +40 point margins indicate a large Democratic victory.

Current Context

Illinois's 5th District is a strongly Democratic-leaning congressional district. In the 2024 election, incumbent Mike Quigley (D) secured 69.0% of the vote (251,025 votes) against Hanson (R), who received 31.0% (112,931 votes), resulting in a substantial margin of victory of 38.0 points, or approximately 138,094 votes [1][2][3]. The Cook Political Report assesses Illinois's 5th Congressional District as "Solid Democratic" for the 2026 election cycle, identifying Mike Quigley (D) as the incumbent and confirming the 2024 general election result at 69.0% for the Democratic candidate [4].
The 2026 election timeline is set, with Democrats favored to win. Key dates for Illinois's 5th Congressional District election in 2026 include a filing deadline of November 3, 2025, a primary election on March 17, 2026, and the general election scheduled for November 3, 2026 [5][4]. Prediction markets currently reflect this strong Democratic advantage; on Polymarket, the Democratic Party is trading at approximately 94% likelihood to win the IL-05 House election in 2026, compared to roughly 6% for the Republican Party, with the market resolving on or around November 3, 2026 [6].
Sources (6)
  1. 1Illinois 5th District election results 2024 live updates | The Washington Postwashingtonpost.com
  2. 2Illinois Fifth Congressional District Election Results 2024nytimes.com
  3. 3Illinois' 5th Congressional District election, 2024 - Ballotpediaballotpedia.org
  4. 4IL-05 2026 | Cook Political Reportcookpolitical.com
  5. 5Illinois' 5th Congressional District election, 2026 - Ballotpediaballotpedia.org
  6. 6IL-05 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Significant Price Movements

Notable price changes detected in the chart, along with research into what caused each movement.

📈 May 06, 2026: 68.0pp spike

Price increased from 14.0% to 82.0%

Outcome: Democrats, 31+ pts

What happened: The provided web research does not contain any information regarding a 68.0 percentage point spike in the prediction market price for "Illinois's 5th District margin of victory" on May 06, 2026. No social media activity from key figures, viral narratives, or traditional news announcements related to such a market movement are reported within the available sources [1]. While the 2024 Democratic presidential vote share for the district was 68.0% [1] and the 2024 congressional vote share was 68.97% for the Democratic candidate [2], these are historical vote percentages, not an explanation for a prediction market price surge. Consequently, the primary driver for the described market movement cannot be identified from the given information.

📈 May 05, 2026: 8.0pp spike

Price increased from 1.0% to 9.0%

Outcome: Democrats, 31+ pts

What happened: Based on the available web research, no specific social media activity or traditional news event related to Illinois's 5th Congressional District on May 05, 2026, has been identified as a primary driver for the 8.0 percentage point spike [3]. The general election is not until November 3, 2026, with primary candidates having been determined on March 17, 2026 [4]. While the district is rated Solid Democratic with a D+19 PVI and the incumbent won by a 37.94-point margin in 2024, no new information on May 5, 2026, appears to have triggered this specific movement [3]. Therefore, social media was irrelevant, and the spike likely represents an internal market adjustment to established district fundamentals rather than a distinct external event.
Sources (4)
  1. 1Illinois' 5th Congressional District election, 2026 (March 17 Democratic primary) - Ballotpediaballotpedia.org
  2. 2Illinois's 5th congressional district - Wikipediaen.wikipedia.org
  3. 3Illinois' 5th Congressional District election, 2026 - Ballotpediaballotpedia.org
  4. 4Illinois House District 5 Primary Election Live Results 2026 - NBC Newsnbcnews.com

4. Market Data

Contract Snapshot

For a "Yes" resolution, the Democratic Party must win the 2026 U.S. House of Representatives election in Illinois's 5th District by 43 percentage points or more; otherwise, it resolves to "No." The margin of victory is calculated by subtracting the vote percentage of the candidate or party immediately behind the Democratic Party from the Democratic Party's vote percentage, with no rounding applied. The market opened on May 5, 2026, closes after the outcome occurs (or by November 3, 2027, if not settled), and results are verified by the official election authority, with the market potentially closing early if certified results are published. Insider trading is prohibited.

Available Contracts

Market options and current pricing

Outcome bucket Yes (price) No (price) Last trade probability
Democrats, 31+ pts $0.91 $0.09 91%
Democrats, 34+ pts $0.84 $0.17 84%
Democrats, 37+ pts $0.75 $0.26 74%
Democrats, 55+ pts $0.14 $0.87 14%
Democrats, 40+ pts $0.66 $0.35 0%
Democrats, 43+ pts $0.56 $0.45 0%
Democrats, 46+ pts $0.43 $0.58 0%
Democrats, 49+ pts $0.32 $0.69 0%
Democrats, 52+ pts $0.22 $0.79 0%

Market Discussion

Current polling indicates Sean Casten (D) is leading Bill Bloomer (R) by 25-30 points in Illinois's 5th District, supported by Casten's substantial fundraising advantage of $2.5 million over Bloomer's less than $200,000, and the district's D+7 Cook Partisan Voting Index [1]. Prediction markets reflect a strong expectation for a Democratic win, with Polymarket showing Democrats at 94% to win [2]; however, explicit margin odds from markets like Kalshi were not located in searches, though Kalshi defines 100 percentage points for uncontested Democratic races [3].

Sources (3)
  1. 1IL-05 Ganador de las elecciones de la Cámara Predicciones... | Polymarketpolymarket.com
  2. 2IL-05 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com
  3. 3Illinois's 5th District margin of victory Odds & Predictions - Kalshikalshi.com

5. Trust Index

Octagon Trust Index Kalshi 83 Good

Order book is critically thin.

Primary risk· Trade quality

How it adds up
Integrity80% of score92Strong
Trade quality20% of score45High Risk

Includes the cost to trade: a $1,000 order can't be filled here because the order book is too thin.

Trust score83Good

Weighted blend with hard caps — a critically weak safety pillar, or a severe trading anomaly, caps the total regardless of the rest. Full methodology · About the Trust Index

Trust profile
Integrity4 screens run · 6 don't apply
Market integrity
90Strong

Outcome is hard to influence

No suspicious activity on any screen

Screened clean
Large tradesNo single trade dominates the tape. Clear
Thin-volume movesNo significant move Clear
Size patternsTape too thin Clear
2 screens not run
Outcome control · doesn't apply to this market type
Thin-leg conviction · doesn't apply to this market type
Info fairness
95Strong

Structural prior — no screens apply

No suspicious activity on any screen

Screened clean
Information exposureNo concentrated group can know the outcome materially early. Clear
4 screens not run
Move vs. catalyst · doesn't apply to this market type
Longshot repricing · doesn't apply to this market type
Pre-broadcast certainty · doesn't apply to this market type
Cross-venue timing · doesn't apply to this market type
Resolution quality
92Strong

Resolution mechanism is dependable

No suspicious activity on any screen

Resolution rules read: Clear

Liquidity
56Thin

Expect slippage beyond small size

4 contracts · worst first · 5 below the volume floor — not scored

Quigley, 34+ pts56
Thin · low confidence

Light recent trading — size may not fill near the screen price.

Quigley, 31+ pts—
No recent trading to measure

No recent trading to measure

Quigley, 40+ pts—
No recent trading to measure

No recent trading to measure

Quigley, 55+ pts—
No recent trading to measure

No recent trading to measure

Move quality
63Mostly confirmed

Most moves carried real volume

4 contracts · worst first · 5 below the volume floor — not scored

Quigley, 31+ pts63
Mostly confirmed · medium confidence

Volume opposes the move over 3d

Quigley, 34+ pts—
No significant move (6h)

Price was stable over the last 6 hours.

Quigley, 40+ pts—
No trading in 4d

No trades in the last 4d — nothing to confirm

Quigley, 55+ pts—
No trading in 5d

No trades in the last 5d — nothing to confirm

Rule clarity
100Clear

Counts toward Resolution quality, not here

4 contracts · worst first · 5 below the volume floor — not scored

Quigley, 31+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 34+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 40+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 55+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Trade quality
45High Risk

Order book is critically thin

Tradable, but expect execution cost beyond small sizes.

Outcome quality 56 (notional-weighted)

$100 order: 3.0c slippage (~3% of a 95c contract)

$1,000 order: book too thin to fill

$10,000 order: book too thin to fill

5 below the volume floor — not scored

Quigley, 31+ pts–Market scoreLiquidity–Move quality63Rule clarity100
Why this score
Liquidity
No recent trading to measure

No recent trading to measure

Move quality
63 · Mostly confirmed · medium confidence

Volume opposes the move over 3d

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 34+ pts56Market scoreLiquidity56Move quality–Rule clarity100
Why 56
Liquidity
56 · Thin · low confidence

Light recent trading — size may not fill near the screen price.

Move quality
No significant move (6h)

Price was stable over the last 6 hours.

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 40+ pts–Market scoreLiquidity–Move quality–Rule clarity100
Why this score
Liquidity
No recent trading to measure

No recent trading to measure

Move quality
No trading in 4d

No trades in the last 4d — nothing to confirm

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Quigley, 55+ pts–Market scoreLiquidity–Move quality–Rule clarity100
Why this score
Liquidity
No recent trading to measure

No recent trading to measure

Move quality
No trading in 5d

No trades in the last 5d — nothing to confirm

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear

underwriting_v1.4 · computed Oct 25, 2026

6. What are the key candidate-filing deadlines and potential retirement announcements from Rep. Mike Quigley that could alter the 2026 IL-05 race dynamics?

Candidate Filing DeadlineNovember 3, 2025 [1][2][3]
Primary Election DateMarch 17, 2026 [1][3]
Rep. Quigley Primary Win Percentage66% (65,965 votes) [4][5]
Key deadlines for the IL-05 race are set. The candidate filing deadline for the 2026 IL-05 race is November 3, 2025 [1][2][3]. The primary election is scheduled for March 17, 2026, with the general election following on November 3, 2026 [1][3]. As of current information, Rep. Mike Quigley has not announced any retirement from Congress and continues his campaign towards the general election [4][3][5].
Rep. Quigley seeks mayoral office while running for Congress. In January 2026, Quigley declared his intention to run for Chicago mayor in 2027, with a formal campaign launch planned after the primary election [6][7][8][9][10]. Despite these mayoral aspirations, he proceeded to file and run for re-election in IL-05 [6][7][8][9][10]. On March 17, 2026, he secured the Democratic primary victory with 66% of the vote, totaling 65,965 votes [4][5]. He is currently campaigning against Tom Hanson, the Republican primary winner, for Congress [4][3][5].
Sources (10)
  1. 1Illinois' 5th Congressional District election, 2026 (March 17 Democratic primary) - Ballotpediaballotpedia.org
  2. 2State and federal candidate filing deadlines for 2026 - Ballotpediaballotpedia.org
  3. 3Illinois' 5th Congressional District election, 2026 - Ballotpediaballotpedia.org
  4. 4Illinois' 5th Congressional District - Ballotpediaballotpedia.org
  5. 5Mike Quigley Wins Democratic Primary For 5th Congressional District Seatblockclubchicago.org
  6. 6U.S. Rep. Mike Quigley plans to run for mayor of Chicago in 2027 - CBS Chicagocbsnews.com
  7. 7Congressman Mike Quigley to run for mayor of Chicago in 2027, saying city is "in crisis" - CBS Chicagocbsnews.com
  8. 8Mike Quigleyen.wikipedia.org
  9. 9Rep. Mike Quigley confirms plans for Chicago mayoral bidyahoo.com
  10. 10U.S. Rep. Mike Quigley says he'll launch mayoral run, fix a 'city in crisis' - Chicago Sun-Timeschicago.suntimes.com

7. How do historical election results since 2022 and ratings from outlets like the Cook Political Report establish the baseline margin for IL-05 in 2026?

2022 IL-05 Election Margin+40.8 points (Quigley) [1][2]
2024 IL-05 Election Margin+38 points (Quigley) [3][4]
Cook PVI IL-05 (2025)D+19 [5][6][7]
IL-05 consistently demonstrates a strong Democratic preference in recent elections. In the 2022 Illinois' 5th Congressional District election, incumbent Quigley secured 69.6% of the vote against Hanson's 28.8%, yielding a significant +40.8-point margin [1][2]. This robust trend continued into the 2024 election, where Quigley received 69% to Hanson's 31%, resulting in a +38-point margin [3][4]. Further underscoring the district's strong Democratic lean, the 2024 presidential election within IL-05 saw Harris receive 68% of the vote compared to Trump's 31% [3].
The Cook Political Report confirms IL-05 as a solidly Democratic district. Its 2025 Partisan Voting Index (PVI) for IL-05 is D+19, which averages the 2020 and 2024 presidential election results [5][6][7]. This classification highlights the district's firm Democratic base. For the upcoming 2026 cycle, with incumbent Quigley running, the Cook Political Report has rated IL-05 as Solid Democrat, indicating a high likelihood of continued Democratic control [8].
Sources (8)
  1. 1Illinois' 5th Congressional District election, 2022 - Ballotpediadocker.ballotpedia.org
  2. 2Illinois' 5th Congressional District election, 2022 - Ballotpediaballotpedia.org
  3. 3Illinois' 5th Congressional District election, 2026 - Ballotpediaballotpedia.org
  4. 42024 IL U.S. House General Election Resultsthegleaner.com
  5. 5The 2025 Cook Partisan Voting Index (Cook PVI℠) | Cook Political Reportcookpolitical.com
  6. 62025 Cook PVI℠: District Map and List (119th Congress) | Cook Political Reportcookpolitical.com
  7. 7Cook Partisan Voting Indexen.wikipedia.org
  8. 8IL-05 2026 | Cook Political Reportcookpolitical.com

8. How do Rep. Mike Quigley's fundraising totals compare with those of any declared Republican challengers for the 2026 cycle, based on FEC reports?

Mike Quigley 2027 Mayoral Committee Collected$154,500 (October 1 to December 31) [1][2][3]
Mike Quigley 2027 Mayoral Committee Cash on Hand$157,424 (at year-end) [1][2][3]
Hanson 2026 Congressional Fundraising$2,500 (as of June 30, 2024) [4][3][5][6]
Representative Mike Quigley's 2026 congressional fundraising data is not currently available. Specific fundraising totals for his 2026 congressional campaign are not disclosed in the provided information. However, his "Friends of Mike Quigley" political committee, which is raising funds for a potential 2027 Chicago mayoral bid, collected $154,500 between October 1 and December 31. This separate committee ended the year with $157,424 saved for that particular endeavor [1][2][3].
Republican challenger Hanson has reported limited fundraising totals so far. As of June 30, 2024, declared Republican challenger Hanson had raised $2,500. Hanson's campaign also maintained a cash-on-hand balance of $475 at that time [4][3][5][6].
Sources (6)
  1. 1dailyherald.com
  2. 2fec.gov
  3. 3thehill.comelections2024.thehill.com
  4. 4ballotpedia.org
  5. 5cbsnews.com
  6. 6ballotpedia.org

9. What do the latest voter registration and demographic data for Illinois's 5th District reveal about its partisan lean heading into the 2026 election?

Cook PVID+19 (for 2026 election) [1][2][3]
Election CategorizationSolid Democratic or Safe Democratic [1]
Median Household Incomeexceeded $113,000 (2023-2024) [4][5][3]
Illinois's 5th District strongly favors Democrats for the 2026 election. The district holds a Cook Partisan Voting Index (PVI) of D+19, indicating its performance was 19 percentage points more Democratic than the national average in the last two presidential elections [1][2][3]. Political analysis outlets such as Cook Political Report, Inside Elections, and Sabato's Crystal Ball consistently categorize IL-05 as "Solid Democratic" or "Safe Democratic" [1]. Historically, the district and its predecessors have been a consistent Democratic stronghold, held by the party for all but four years since 1909 [3]. The incumbent, Democrat Mike Quigley, has served the district since winning a 2009 special election and has secured re-election multiple times [4][3][6][7].
The district is an affluent, highly educated, and diverse urban area. As of 2024, Illinois's 5th District has a population of 773,710 residents and is 100% urban, encompassing over 20 neighborhoods on Chicago's North Side and numerous suburban towns [4][3]. Demographically, it is predominantly non-Hispanic White, making up approximately 70.3% to 71.3% of the population [4][3]. Non-Hispanic Asians constitute about 10.7%, and Hispanic individuals account for roughly 11.7% to 12.4% [4][5][3]. The district is notably affluent, with a median household income exceeding $113,000 in 2023-2024 and a low poverty rate of 7.13% in 2023 [4][5][3]. Furthermore, IL-05 boasts high levels of educational attainment, with a bachelor's degree attainment rate of 67%, making it the fourth-most college-educated seat in the United States [4][8].
Sources (8)
  1. 1ballotpedia.org
  2. 2wikipedia.orgen.wikipedia.org
  3. 3wikipedia.orgen.wikipedia.org
  4. 4grokipedia.com
  5. 5datausa.io
  6. 6ballotpedia.org
  7. 7ballotpedia.org
  8. 8cookpolitical.com

10. What is the potential impact of the national political environment, specifically President Biden's approval rating, on Democratic turnout in Illinois's 5th district for the 2026 midterms?

President Biden Average Approval Rating47.3% (as of May 2026) [1]
Average House Seats Lost (Approval < 50%)37 seats [2]
IL-05 Cook Partisan Voting IndexD+19 [3][4]
President Biden's approval rating suggests challenges for Democrats in midterms. As of May 2026, President Biden's average approval rating was 47.3% [1]. Historically, presidential parties typically lose House seats in midterm elections when the president's approval rating is below 50%, a trend observed in 20 out of 22 midterms since 1938 [5][2]. In such scenarios, parties facing approval ratings below 50% have, on average, lost approximately 37 House seats [2]. This lower approval can also lead to reduced Democratic voter turnout nationally, while potentially energizing the opposition [2].
Illinois's 5th district strongly favors Democrats, defying national headwinds. Despite these national trends, Illinois's 5th congressional district maintains a significant Democratic lean, evidenced by its Cook Partisan Voting Index (PVI) of D+19 [3][4]. This PVI indicates that the district votes 19 percentage points more Democratic than the national average [3]. The 2021 redistricting further solidified this Democratic strength, contributing to the incumbent securing 67.9% of the vote and a 37.4-point winning margin in the 2022 general election [6]. Given these factors, the district is rated as "Solid D" for 2026 by the Cook Political Report [7].
Sources (7)
  1. 1ballotpedia.org
  2. 2forbes.com
  3. 3ballotpedia.org
  4. 4wikipedia.orgen.wikipedia.org
  5. 5brookings.edu
  6. 6grokipedia.com
  7. 7cookpolitical.com

11. What Could Change the Odds

Key Catalysts

The upcoming election cycle for Illinois's 5th Congressional District presents several key dates that could influence market probabilities. The filing deadline is set for November 3, 2025, followed by the primary on March 17, 2026, and the general election on November 3, 2026 [1][2][3]. These milestones are expected to drive market activity as candidates are finalized and campaign dynamics evolve, potentially impacting the explicit margin-of-victory markets available on platforms like Kalshi [4].
Market expectations for IL-05 currently show a strong lean towards the Democratic Party, with Ballotpedia assigning a Cook Partisan Voter Index of D+19 [5][2]. This is directionally consistent with the current crowd probability on Polymarket, which heavily favors the Democratic Party at 94% to win the House election [6]. Any developments challenging this established Democratic baseline, such as the emergence of an unexpectedly strong challenger to the incumbent Mike Quigley (D) [3] or significant shifts in political sentiment within the district, could serve as a catalyst for changes in margin-of-victory forecasts.

Key Dates & Catalysts

  • Expiration: November 03, 2027
  • Closes: November 03, 2027
Sources (6)
  1. 1Illinois' 5th Congressional District election, 2026 (March 17 Democratic primary) - Ballotpediaballotpedia.org
  2. 2Illinois' 5th Congressional District election, 2026 - Ballotpediaballotpedia.org
  3. 3IL-05 2026 | Cook Political Reportcookpolitical.com
  4. 4Illinois's 5th District margin of victory Odds & Predictions - Kalshikalshi.com
  5. 5Illinois' 5th Congressional District - Ballotpediaballotpedia.org
  6. 6IL-05 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com